PDR Health


What is erythromycin?

Erythromycin is an antibiotic. It is used to treat certain types of infections caused by bacteria.

Erythromycin may also be used for purposes not listed in this medication guide.

You should not use erythromycin if you are allergic to it, or if:

you have liver disease; or

if you are taking any other medicine that contains erythromycin (E.E.S., E-Mycin, Erymax, Ery-Tab, PCE, Pediazole, Ilosone).

Health Benefits

Erythromycin is used to treat a wide variety of bacterial infections. This medication can also be used to prevent certain types of bacterial infections, such as rheumatic fever.

Side Effects

Common side effects of erythromycin include:

nausea, vomiting, stomach pain;

diarrhea; or

vaginal itching or discharge.

rare side effects include:

jaundice (yellowing of the skin or eyes);

dark urine;

pale stools; or

loss of appetite, upper stomach pain (that may spread to your back), nausea, jaundice (yellowing of your skin or eyes).


The usual adult dose of erythromycin is 250 mg to 500 mg four times daily. For children, the dosage is based on weight.

Erythromycin should be taken with food or milk.


Erythromycin can interact with a number of other medications. Be sure to tell your doctor about all the medications you are taking, including over-the-counter drugs, vitamins, and herbal supplements.

Mechanism of Action

Erythromycin works by inhibiting protein synthesis in bacteria. This action prevents the bacteria from growing and multiplying, thereby killing them.


Erythromycin is rapidly absorbed from the gastrointestinal tract. It is widely distributed throughout the body, including crossing the blood-brain barrier. Erythromycin is metabolized in the liver and eliminated mainly in the bile.

Alternatives to Erythromycin

There are many alternatives to erythromycin available. Some of these include other antibiotics, such as penicillin, cephalosporins, and fluoroquinolones. There are also a number of antifungal and antiviral medications that can be used as alternatives to erythromycin. If you have any questions about alternatives to erythromycin, be sure to ask your doctor or pharmacist.

Clinical Trials

The efficacy of erythromycin has been demonstrated in a number of clinical trials.

In a study published in the New England Journal of Medicine, erythromycin was found to be effective in treating Legionnaires’ disease.

In another study, erythromycin was found to be effective in treating community-acquired pneumonia.

A third study showed that erythromycin was effective in treating skin and soft tissue infections.

Erythromycin has also been shown to be effective in treating a number of other infections, including diphtheria, syphilis, and chlamydia.


Erythromycin was first isolated in 1952 from the bacterium Streptomyces erythraeus. It was introduced into clinical use in 1954.

Erythromycin has been used for a number of years and has an excellent safety record.


Erythromycin is a well-established antibiotic with a long history of use. It is generally well-tolerated and has a low incidence of side effects.

Erythromycin is approved for the treatment of a wide variety of bacterial infections.

How is it supplied?

Erythromycin is supplied as a capsule, tablet, suspension, gel, and ointment.

Symptoms of an Overdose

Erythromycin overdose may include:

nausea, vomiting, stomach pain;


dizziness, drowsiness; or


Pregnancy and Erythromycin

Erythromycin is generally considered safe for use during pregnancy. However, as with all medications, be sure to tell your doctor if you are pregnant or planning a pregnancy.

There is some evidence that erythromycin may increase the risk of certain birth defects, such as pyloric stenosis. Therefore, erythromycin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Is Penicillin more effective than Erythromycin?

There is no definitive answer to this question. Both penicillin and erythromycin are effective against a wide variety of bacteria. In general, erythromycin may be more effective against certain types of bacteria, while penicillin may be more effective against others. Ultimately, the decision about which antibiotic to use should be made by your doctor.